1. Field of the Invention
The present invention is generally concerned with dynamic wheel balancers, and more particularly is directed to a fixture for securely supporting a cycle wheel, i.e. a motorcycle wheel, on the spindle of a conventional dynamic wheel balancer, so that the balancer can be used with cycle wheels as well as standard automobile and truck wheels.
2. Description of the Prior Art
Dynamic wheel balancers typically include a rotatable spindle upon which the wheel is mounted during the balancing operation. Force measuring devices, e.g., piezoelectric crystals, detect lateral forces generated by the spindle during its rotation. These forces are caused by imbalance within the wheel, and provide an indication of the amount and location of weights to be added to the wheel to bring it into proper balance. Such balancers can measure in one or two planes. That is, they can determine the amounts of weight to be added in the center plane of the wheel or in two locations on the wheel, most typically the two rims of the wheel. Dynamic balancers of this type are disclosed, for example, in copending U.S. patent application Ser. No. 236,558 filed Feb. 20, 1981, now U.S. Pat. No. 4,435,982, and Ser. No. 444,885, filed Nov. 29, 1982.
Since most dynamic balancers are primarily used for balancing automobile and truck wheels, their spindles are fitted with support structure that facilitates the mounting of such wheels. This support structure generally includes an annular flange that is fixedly attached to the spindle. The flange provides a planar support surface against which the inside of the wheel bears. After the wheel is placed on the spindle, a conically shaped hub is threaded onto the spindle with its apex facing the flange. The hub serves to center the wheel on the spindle as well as force it against the flange, thus providing a stable mount that rigidly secures the wheel to the spindle.
While this mounting arrangement is suitable for standard automobile and truck wheels, it is not particularly adapted for motorcycle wheels and the like. More specifically, the motorcycle wheel does not have a suitable surface that can bear against the flange and receive the force provided thereby when the conical hub is tightened against the outside of the wheel. Rather, the inner circumference of the flange rests against the spokes of the wheel. If the conical hub is tightened against the wheel with sufficient force to hold the wheel firmly in place, the spokes of the wheel can be bent by the inner rigid edge of the flange, resulting in permanent damage to the wheel.
In an effort to circumvent this problem, one prior art adaptor for motorcycle wheels employs a plate or bar that is adjacent the flange and that has fingers which engage the spokes of the wheel. While this arrangement avoids the damaging contact between the flange of the balancer and the spokes of the wheel, it is not totally satisfactory in use. More particularly, it does not provide a sufficiently rigid mounting for the wheel that prevents the wheel from oscillating during rotation, making it difficult to obtain a truly accurate reading of imbalance. If the conical hub of the balancer is tightened against the wheel to reduce oscillation, damage to the wheel can again result from the excessive force placed on the hub of the wheel.
In addition, this type of adapter is awkward and time consuming to use, since the fingers must be separately adjusted for each different type of cycle wheel. Furthermore, its applications are limited to spoked wheels. It cannot be used with solid wheels of the type found on most motor scooters or with light alloy disc wheels that are becoming increasingly popular on motorcycles.